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<Paper uid="P96-1031">
  <Title>An Efficient Compiler for Weighted Rewrite Rules</Title>
  <Section position="5" start_page="236" end_page="237" type="concl">
    <SectionTitle>
6. Conclusion
</SectionTitle>
    <Paragraph position="0"> We briefly described a new algorithm for compiling context-dependent rewrite rules into finite-state transducers. Several additional methods can be used to make this algorithm even more efficient.</Paragraph>
    <Paragraph position="1"> The automata determinizations needed for this algorithm are of a specific type. They repre- null sent expressions of the type ~*C/ where C/ is a regular expression. Given a deterministic automaton representing C/, such determinizations can be performed in a more efficient way using failure functions (Mohri, 1995). Moreover, the corresponding determinization is independent of ~ which can be very large in some applications. It only depends on the alphabet of the automaton representing C/.</Paragraph>
    <Paragraph position="2"> One can devise an on-the-fly implementation of the composition algorithm leading to the final transducer representing a rule. Only the necessary part of the intermediate transducers is then expanded for a given input (Pereira et al., 1994).</Paragraph>
    <Paragraph position="3"> The resulting transducer representing a rule is often subsequentiable or p-subsequentiable. It can then be determinized and minimized (Mohri, 1994). This both makes the use of the transducer time efficient and reduces its size.</Paragraph>
    <Paragraph position="4"> We also indicated an extension of the theory of rule-compilation to the case of weighted rules, which compile into weighted finite-state transducers. Many algorithms used in the finite-state theory and in their applications to natural language processing can be extended in the same way.</Paragraph>
    <Paragraph position="5"> To date the main serious application of this compiler has been to developing text-analyzers for text-to-speech systems at Bell Laboratories (Sproat, 1996): partial to more-or-less complete analyzers have been built for Spanish, Italian, French, Romanian, German, Russian, Mandarin and Japanese. However, we hope to also be able to use the compiler in serious applications in speech  deterministic automaton r representing PS = $ $ E~0 &gt; P&gt;0E&gt;0- &gt; E&gt;0 versus the log of the number of arcs in the automaton obtained by determinization of r.</Paragraph>
    <Paragraph position="6"> recognition in the future.</Paragraph>
  </Section>
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